It’s as old as King David and as modern as Tiger Woods. It affects macho men like Arnold Schwarzenegger and wimps like Woody Allen. Offenders can be serious men of great responsibility like General David Petraeus, as well as silly little men like former Congressman Anthony Weiner. It’s infidelity, and it is rampant in our culture.

The characters in Death in Panama unfortunately reflect what I saw when I lived there. Maybe it was the hot weather and beautiful Panamanian women that made them forget how they’d been raised. Or maybe the heat simply made them a little crazy. In any event, it was not uncommon to see men—who had probably been faithful church-goers back home—casually disregard their marriage vows.

Today, infidelity is an epidemic everywhere. Panama is no worse than Atlanta or Dallas or Houston or, certainly, Washington, D.C. The Internet has made it easy to find willing accomplices—sometimes paid, sometimes not.

The nagging question for me is: Why? Why do men feel the need to forsake the women to whom they pledged their love?

Research suggests that the answer is not what you might think. That is, it’s not for sex.

In his best-selling book, The Truth About Cheating, marriage counselor M. Gary Neuman reports on his survey of cheating and non-cheating men. Forty-eight percent of the men he surveyed said that the primary reason they cheated was because of emotional dissatisfaction. Only eight percent said sexual dissatisfaction was the main factor. “Our culture tells us that all men need to be happy is sex, says Neuman. “But men are emotionally driven beings too. They want their wives to show them that they’re appreciated, and they want women to understand how hard they’re trying to get things right.”

So why do men feel unappreciated and misunderstood? Neuman concludes that the problem is cultural. “Most men consider it unmanly to ask for a pat on the back, which is why their emotional needs are often overlooked,” Neuman says.

His advice to women: “Create a marital culture of appreciation and thoughtfulness—and once you set the tone, he’s likely to match it.”

Relationships are complicated, and I don’t profess to have the answers. But I do think that it’s a problem that both men and women need to work on. Neuman found that the cheaters were not, as one might expect, uncaring cads. On the contrary, sixty-six percent of the cheaters said they felt guilt during the affair. And sixty-eight percent of them never dreamed they’d be unfaithful in the first place.

So, if guilt isn’t enough to stop men from cheating, what is?

Although it might sound like a throwback to the 1950s, Neuman suggests that women focus on their own behavior, because that’s something they completely control. He says they should show their appreciation, prioritize time together, and initiate sex more. In short, give your man man a reason to keep you at the front of his mind.